Author: alc
Date: Tue Sep 1 06:21:12 2015
New Revision: 287344
URL: https://svnweb.freebsd.org/changeset/base/287344
Log:
Handle held pages earlier in the inactive queue scan.
Reviewed by: kib
Sponsored by: EMC / Isilon Storage Division
Modified:
head/sys/vm/vm_pageout.c
Modified: head/sys/vm/vm_pageout.c
==============================================================================
--- head/sys/vm/vm_pageout.c Tue Sep 1 06:05:43 2015 (r287343)
+++ head/sys/vm/vm_pageout.c Tue Sep 1 06:21:12 2015 (r287344)
@@ -1125,31 +1125,45 @@ vm_pageout_scan(struct vm_domain *vmd, i
* different position within the queue. In either
* case, addl_page_shortage should not be incremented.
*/
- if (!vm_pageout_page_lock(m, &next)) {
- vm_page_unlock(m);
- continue;
+ if (!vm_pageout_page_lock(m, &next))
+ goto unlock_page;
+ else if (m->hold_count != 0) {
+ /*
+ * Held pages are essentially stuck in the
+ * queue. So, they ought to be discounted
+ * from the inactive count. See the
+ * calculation of the page_shortage for the
+ * loop over the active queue below.
+ */
+ addl_page_shortage++;
+ goto unlock_page;
}
object = m->object;
- if (!VM_OBJECT_TRYWLOCK(object) &&
- !vm_pageout_fallback_object_lock(m, &next)) {
- vm_page_unlock(m);
- VM_OBJECT_WUNLOCK(object);
- continue;
+ if (!VM_OBJECT_TRYWLOCK(object)) {
+ if (!vm_pageout_fallback_object_lock(m, &next))
+ goto unlock_object;
+ else if (m->hold_count != 0) {
+ addl_page_shortage++;
+ goto unlock_object;
+ }
}
-
- /*
- * Don't mess with busy pages, keep them at at the
- * front of the queue, most likely they are being
- * paged out. Increment addl_page_shortage for busy
- * pages, because they may leave the inactive queue
- * shortly after page scan is finished.
- */
if (vm_page_busied(m)) {
- vm_page_unlock(m);
- VM_OBJECT_WUNLOCK(object);
+ /*
+ * Don't mess with busy pages. Leave them at
+ * the front of the queue. Most likely, they
+ * are being paged out and will leave the
+ * queue shortly after the scan finishes. So,
+ * they ought to be discounted from the
+ * inactive count.
+ */
addl_page_shortage++;
+unlock_object:
+ VM_OBJECT_WUNLOCK(object);
+unlock_page:
+ vm_page_unlock(m);
continue;
}
+ KASSERT(m->hold_count == 0, ("Held page %p", m));
/*
* We unlock the inactive page queue, invalidating the
@@ -1164,7 +1178,7 @@ vm_pageout_scan(struct vm_domain *vmd, i
* Invalid pages can be easily freed. They cannot be
* mapped, vm_page_free() asserts this.
*/
- if (m->valid == 0 && m->hold_count == 0) {
+ if (m->valid == 0) {
vm_page_free(m);
PCPU_INC(cnt.v_dfree);
--page_shortage;
@@ -1208,18 +1222,6 @@ vm_pageout_scan(struct vm_domain *vmd, i
goto drop_page;
}
- if (m->hold_count != 0) {
- /*
- * Held pages are essentially stuck in the
- * queue. So, they ought to be discounted
- * from the inactive count. See the
- * calculation of the page_shortage for the
- * loop over the active queue below.
- */
- addl_page_shortage++;
- goto drop_page;
- }
-
/*
* If the page appears to be clean at the machine-independent
* layer, then remove all of its mappings from the pmap in
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